Spin echo

Spin echo

Spin echo refers to a technique used in magnetic resonance imaging (MRI) where a 90° pulse is applied in the x direction to rotate the spins into the x-y plane. This technique is used to obtain proton density weighted images and is one of many MR imaging techniques where the spin echo is used instead of the free induction decay (FID).From: Radiological Sciences Dictionary: Keywords, names and definitions [2019], Quantifying food drying rates from NMR/MRI experiments: Development of an online calibration system [2019], Polymer Characterization [2017]

Magnetic Resonance Imaging

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Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020

Suzanne Amador Kane, Boris A. Gelman

The problem in trying to measure relaxation times is that the shortest relaxation time dominates the time behavior of the signal. Unfortunately, this is usually T2*, a quantity that has nothing to do with the body. To measure T1 or T2, a more sophisticated method must be used to separate out these more interesting time behaviors. To accomplish this, most imaging techniques use pulse sequences: many RF pulses emitted and detected in a series. The free induction signals emitted by the body's nuclei after they have been excited by a pulse sequence are measured in order to tease out information about T1 and T2. One commonly used pulse sequence technique is called spin-echo imaging. In understanding this method, you will gain an appreciation of the general ideas behind MRI. (Note that the “echoes” in question only share a name with those used in ultrasound imaging. The underlying physics is very different.)

Quantifying food drying rates from NMR/MRI experiments: Development of an online calibration system

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Published in Drying Technology, 2019

Yichuan Jiang, Xin Jin, Fangfang Xu, Xiao Dong Chen

For the MRI measurements, SPIN ECHO sequence was used to obtain proton density weighted images. An image was taken in every 30 min for each sample. The main parameters were slice width = 4 mm, slice gap = 1 mm, time repetition (TR) = 2000, time echo (TE) = 15 ms, average =16.

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Magnetic Resonance Imaging

Quantifying food drying rates from NMR/MRI experiments: Development of an online calibration system